Electroplating is a process for putting a metallic plate or coating on a conducting surface by using an electric current. The surface to be plated is connected to the negative end of a source of electricity and it is placed in a plating solution containing ions of the metal with which it is to be plated. The conducting surface to be plated when thus connected is referred to as the "cathode". The positive end of the electrical source is connected to another conductor which is of the same composition as the metal plate desired. It is commonly referred to as the "anode" and it is also placed in the plating bath. A direct electrical current is passed through the bath to separate metal ions from the plating bath and cause the metal to be deposited on the cathode.
Alkaline plating baths containing cyanide are employed for the commercial electrodeposition of most copper alloys, such as, brass which contains approximately 70% copper and 30% zinc, white brass which contains 50% zinc and about 50% copper, high copper alloys which contain about 90% copper and 10% zinc, bronze which contains copper and tin and copper and lead alloys.
The use of alkaline cyanide plating baths present spent bath disposal problems. Before the spent cyanide baths or subsequent rinses can be discarded, they must meet pollution control effluent requirements which requires costly cyanide destruction. Therefore, a need exists for a cyanide-free plating bath for the electroplating of copper alloys.
In my earlier applications, I disclosed cyanide-free plating baths which can be used for the commercial electrodeposition of copper and zinc alloys. However, a need also exists for cyanide-free plating baths for copper-tin (bronze) and copper-lead alloys.